Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to a push-button switch, in particular, to a push-button switch having an overload protection function and a circular type actuation mechanism, in which a rotatable actuator is used to circularly actuate the connection of terminals so as to obtain a simple structure and a small volume.
2. Description of the Related Art
There are many types of push-button switches for various applications, such as one having a turn-on indicating lamp and one providing an overload protection function. As to one having an overload protection function, there are also several kinds of protection principles or mechanisms being adopted. For example, both the blowout of a fuse wire and the thermal deformation of a bimetal blade have ever been adopted as a trigger source for an overload protection. However, the fuse wire is not repetitive and thus its utility rate gradually decreases. As for the thermal bimetal blade, there are many kinds of mechanism, such as those disclosed in U.S. Pat. Nos. 5,786,742, 5,223,813, 4,937,548, 4,661,667, 4,931,762, 5,451,729, and 4,704,594.
Moreover, there has been disclosed a conventional switch in which a slide-to-rotate mechanism comprising a push-button and a rotatable slider is used. One end of the rotatable slider is installed with a pair of conduction pads for alternatively contacting with and thus conducting two terminals in the switch in response to the rotation of the slider. However, the contacts of such a kind of switch wear very soon due to the spark resulting form the friction between the conduction pads and the terminals. Moreover, such a kind of switch is not provided with a function of overload protection and thus does not meet the modern requirement of safety.
The main object of the present invention is to provide a push-button switch having an overload protection function and a circular type actuation mechanism, which has a simple structure and occupies a small space.
To achieve its objects above, this invention provides a push button switch comprising a housing, an actuating mechanism, and a circuit mechanism with overload protection, wherein;
the housing is provided with a mechanism accommodation chamber and a button guide;
the actuating mechanism comprising:
a button having an upper end and a lower end as well as a cavity at its lower end guided by the button guide in sliding,
a transferring slider having an upper end slipped into the cavity of the button such that it can be rotated at a predetermined angle in response to the sliding of the button, a lower end, and a longitudinal recess opening to the lower end;
a push rod having an upper end slipped into the recess of the transferring slider such that it can be rotated along with the rotation of the transferring slider, a lower end, and a pair of first actuators located between the upper and the lower ends for actuating the circuit mechanism in response to the rotation of the transferring slider;
a biasing spring forcing the button and the transferring slider up; and
the circuit mechanism including a first terminal, a second terminal, and a conduction element for alternatively connecting the first and the second elements in response to the action of the pair of first actuators and disconnecting the first and the second elements in response to overload.
By means of the above structure, since the switch is turned on/off by a slide-to-rotate mechanism, and the circuit mechanism can provide an over-load protection function, the switch will have a compact volume, reduce wearing, and thus increase lifetime thereof.